Supporting Your Thyroid: Nutrients, Toxins, and What You Can Do

When it comes to thyroid health, many people think only of iodine. But in my experience working with women over the years, I’ve seen time and again that a range of nutrients, environmental exposures, and even food choices can all play a significant role in how well the thyroid is functioning.

It’s not uncommon for patients to feel like something is off, even when their blood tests are technically within range. And sometimes, by identifying and correcting simple deficiencies, like selenium, iron, or vitamin D, we’ve been able to improve thyroid function naturally and even reduce reliance on high-dose levothyroxine. Here’s what you need to know.

Selenium
Selenium is a trace mineral that the thyroid relies on for two key functions: producing active thyroid hormone (T3) and protecting itself from inflammation. Low selenium is common and can be a trigger for autoimmune thyroid issues like Hashimoto’s.

Selenium is found in foods like Brazil nuts (1–2 per day is usually plenty), eggs, seafood, chicken, and sunflower seeds. In some people, supplementation is needed, but it must be done carefully, as too much can be harmful. This is something we review on a case-by-case basis.

Iodine
Iodine is essential for thyroid hormone production. Most people in the UK get enough through a varied diet, though dairy-free or vegan diets may reduce intake. Seaweed, white fish, shellfish, and eggs are good sources.

However, it’s not just about getting enough iodine, too much of certain other compounds (like fluoride, bromine, or raw cruciferous vegetables) can block iodine’s effect in the thyroid. We sometimes see this in people who have good iodine levels but still have symptoms.

Bromine
Bromine is in the same chemical family as iodine and can compete with it in the thyroid gland. It’s found in some soft drinks, baked goods, fire retardants, and pool chemicals. If your iodine intake is optimal, bromine likely won’t be an issue, but if iodine is low, excess bromine may affect hormone production.

Reducing processed foods and using non-toxic household and personal care products can help lower your exposure.

Filtered Water (Why This Matters in the UK)
In some countries, arsenic exposure from private well water is a real concern. In the UK, this is rare, but that doesn’t mean our tap water is perfect. Chlorine, microplastics, and trace contaminants can add to your overall toxic load.

Many of my patients choose to use a high-quality water filter at home, to reduce everyday exposures that can subtly affect thyroid and hormone health.

Iron
Your body needs iron to convert T4 (inactive thyroid hormone) into T3 (the active form). We often check ferritin (your iron storage marker), and if it’s below 80 µg/L, it may affect how well your thyroid is working.

Red meat, lentils, and leafy greens are good sources, and combining these with vitamin C (like lemon juice or red pepper) improves absorption.

Tyrosine
Tyrosine is an amino acid and a building block for thyroid hormones. Low protein diets or high stress may reduce its availability. Turkey, eggs, dairy, almonds, and tofu all provide tyrosine.

Vitamin D
Vitamin D helps regulate the immune system, which is particularly important in autoimmune thyroid conditions. In the UK, many people are deficient, especially in winter.

We test and supplement if needed, aiming for optimal, not just “normal”, levels.

Toxic Metals: Arsenic, Mercury, and Cadmium
Some environmental toxins can bind to nutrients like selenium and interfere with thyroid function. Arsenic (found in rice, seafood, wine), mercury (in large fish like tuna), and cadmium (from cigarettes or certain grains) all contribute.

These are things we test for when relevant, especially in patients with unexplained fatigue, hormone issues, or autoimmune thyroid disease.

Finally…
Optimising thyroid health isn’t just about chasing a diagnosis or increasing medication. It’s about understanding the wider picture: what you eat, how your body absorbs and uses nutrients, your environment, and your individual symptoms.

In clinic, we use testing where needed, but also look at your diet, stress levels, and supplement use. For some women, addressing these root causes has made a huge difference in how they feel, and has even reduced the need for high-dose thyroid medication.

If you’re curious about your own thyroid health or suspect something is being missed, it’s worth exploring. Supporting the thyroid is as much about what you take out (toxins) as what you put in (nutrients). And small changes can make a big difference!

36y female, tired, weight gain, hair loss
Bloods with GP – normal!
TSH (thyroid stimulating hormone) checked and normal!
Full blood count checked but not a ferritin level

We checked a full female hormone profile, Thyroid panel, including T4, T3 and autoantibodies, ferritin. In addition we checked selenium, iodine, zinc, toxins by doing a simple functional medicine test to look at urinary excretion of these amongst others! This showed a low normal T4 and T3 level, low ferritin (although in ‘normal range’), very low level of selenium and slightly high mercury levels. We took a holistic, root cause approach, and without treating with Levothyroxine, we were able to normalise this lady’s bloods and more importantly, improve her symptoms.